Autonomous weapon system

ABSTRACT

An autonomous weapon system including weapon ( 9 ) and weapon mounting system ( 7, 8 ) operable to point the weapon ( 9 ) in accordance with input control signals. The weapon system includes a sensor ( 2 ) to acquire images and other data from a target zone and an image processor ( 3 ) to process acquired image data and identify potential targets ( 1 ) according to predetermined target identification criteria. Targeting system ( 4, 5 ) provides input control signals to the weapon mounting system ( 7, 8 ) to point the weapon ( 9 ) for firing at potential targets ( 1 ). A control system operates targeting system ( 4, 5 ) and fires the weapon ( 9 ) at selected targets ( 1 ) according to a predetermined of rules of engagement. The rules of engagement include combat, peacekeeping or policing scenarios. Remotely located operator ( 10 ) may amend the rules of engagement, or override the control system as required.

FIELD OF THE INVENTION

This invention relates generally to autonomous direct fire weaponsystems, being weapon systems that engage targets with no requirementfor human intervention or support at the time of engagement, and withdirect fire, meaning that a line-of-sight exists between the weapon andthe target.

BACKGROUND ART

Direct fire weapons are weapons that require a line-of-sight between theweapon and the target. Examples of direct fire weapons include rifles,machine guns, canon, short range missiles and directed energy weapons.Examples of indirect fire weapons include artillery, mortars, andlong-range missiles.

Until the middle of the 20^(th) century, direct fire weapons were firedmanually by a gunner positioned directly behind the weapon. Theadvantages of remote operation (e.g. of machine guns during trenchwarfare) were observed in the early 20^(th) century, but the technologydid not exist to allow remote operation without substantially degradingoverall combat effectiveness.

By 1980 it was widespread practice to include as secondary armament on amain battle tank, small arms with either remote control or armour cover,or both. Small arms, generally defined as ballistic weapons with acalibre of less than 40 mm, are direct fire weapons.

By 1990 the increased emphasis on maximizing both mobility and firepowerresulted in various proposals for remotely operated weapon stations, inwhich small arms are mounted on motorized brackets and remotelyoperated. Typically these systems comprise a machine gun roof-mounted ona lightly armored or unarmored vehicle, and operated under manualcontrol from within the vehicle.

These systems offer several advantages, including:

-   -   the use of a remote gunner lowers the center of mass of the        weapon system, allowing heavier weapons to be mounted on lighter        vehicles without compromising stability;    -   the relocation of the gunner obviates the need for a turret,        allowing weight savings that lead to increased mobility;    -   protection of the gunner improves weapon aiming and combat        effectiveness;    -   the relocation of the gunner hardens the weapon system as a        target, making it more difficult to disable than a manned        weapon; and    -   vehicle hull penetration by the weapon system can be reduced to        small mounting holes, thus increasing the survivability of the        vehicle. The large hole required for a human operator is not        required.

More recently, gyro-stabilized remotely-controlled weapon systems havebeen proposed (Smith et al, U.S. Pat. No. 5,949,015 dated Sep. 7, 1999).These gyro-stabilized remote weapon control systems have the additionaladvantage that the aiming point of the weapon may be renderedsubstantially independent of motion of the weapon platform.

Notwithstanding the advantages of remote weapon systems, theirshortcomings include:

-   -   Poor accuracy. The use of manual weapon pointing, even if        stabilized for weapon platform motion, does not allow optimum        use of weapons. The most common and inexpensive direct-fire        weapons have inherent accuracy that exceeds the ability of human        gunners to aim the weapon.    -   Poor ergonomics. Typical implementations of remote weapon        systems require int nse multi-tasking of the remot gunner under        combat stress, particularly if the weapon is vehicle-mounted.        This reduces the effectiveness of the weapon system.    -   Poor stabilization. Gyro-stablized weapon systems seek to        maintain weapon aiming accuracy by compensating for the motion        of the weapon platform. For each axis of potential motion of the        weapon, gyro is required, as well as a corresponding        servo-controlled axis on the weapon mount. This results in        costly systems that do not take into account movement of the        target, and are of limited use in realistic combat situations        involving target motion.

DISCLOSURE OF THE INVENTION

The invention is an autonomous weapon system, being a weapon system thatcan engage targets with no human intervention at the time of engagement.

In one broad aspect this invention provides an autonomous weapon systemincluding a weapon to be fired at a target; a weapon mounting systemoperable to point the weapon in accordance with input control signals; asensor system to acquire images and other data from a target zone; imageprocessing means to process said acquired images or data and identifypotential targets according to predetermined target identificationcriteria; targeting means to provide said input control signals to saidweapon mounting system to point the weapon for firing at a selected oneor more of said potential targets; firing control means to operate saidtargeting means and fire the weapon at selected ones of said potentialtargets according to a predetermined set of rules of engagement.

Preferably, the autonomous weapon system (“AWS”) further includes acommunication means that allow authorized users of the system to update,upgrade, modify or amend the software and firmware controlling theoperation of the system or monitor its operation. The communicationmeans may provide for the overriding of the firing control means toprevent firing of the weapon. The communication means may also providefor amendment of the rules of engagement at any time during operation ofthe system. The communication means can preferably be used to updatedata files in the weapon system, including those files providing athreat profile to determine the predetermined target identificationcriteria used by the processing means to identify potential targets.

The sensor system preferably includes one or more cameras operating atthe visible, intensified visible or infrared wavelengths and producingimages in digital form, or compatible with digital processing.Preferably, the effective focal length of one or more camera can bevaried by either optical or digital zoom to allow closer scrutiny ofpotential targets.

Preferably, the image processing means includes one or more digitalsignal processors or computers that provide image enhancement and targetdetection, recognition, or identification based on imagecharacteristics. The image processing means may include pre-configuredthreat profiles to allow both conventional and fuzzy logic algorithms toefficiently seek targets according to the level of threat posed byspecific targets, or the probability of encountering a specific target,or both.

The targeting means preferably provides the input control signals basedon pointing corrections required for the weapon to hit the targets. Thecontrol signals can be provided in either digital or analogue form.

The firing control means preferably includes a fail-safe control of thefiring of the weapon by reference to specific rules of engagement storedwithin the system. These specific rules of engagement include variouscombat, peace-keeping, or policing scenarios. The rules of engagementare preferably interpreted by the firing control means in context withthe threat profile, to provide both lethal and non-lethal firingclearances without human intervention.

Preferably, an authorized user selects the set of rules of engagement tobe used prior to deployment of the AWS. The authorized user may amendthose rules at any time that communications are available with the AWS.The set of rules of engagement may preferably retainan enduring veto(exercisable by an authorized user) on the use of lethal force, or eventhe discharge of the weapon in warning mode. For example, one set ofrules of engagement may prohibit the weapon from firing aimed lethalshots under any circumstances in a peace-keeping situation, insteadallowing both warning and non-lethal firing to be undertaken. In aconvention combat scenario the rules of engagement may include means todiscriminate between combatants and non-combatants.

Preferably, the AWS has track processing means to process said acquiredimages or data to determine the correct pointing angles for the weaponto compensate for platform or target motion. The track processing meansmay include one or more digital signal processors that obtaininformation relating to target motion relative to the weapon or itsplatform from one or more locations within one or more fields of view ofeach sensor that the target(s) occupy, and/or from the apparent motionover time of the target(s) in such fields of view. The accuracy of thetrack processing means is preferably enhanced by resolving all motion toa local quasi-inertial reference frame so that the track processingmeans has access to data from such a frame, either within the AWS orexternal to it.

The AWS may have correction processing means to determine corrections tothe weapon pointing angles to compensate for weapon, ammunition,environmental, target range and/or platform orientation. Preferably, thecorrection processing means includes a computer or digital processorthat computes weapon pointing corrections to allow for munitions dropdue to target range and/or other factors. These factors include aimingcorrections for temperature, atmospheric pressure, wind, weapon cant,target elevation, ammunition type, weapon age, and factors unrelated totarget or weapon platform motion.

Preferably, an aim processing means is provided on the AWS to determinethe correct weapon pointing angles based on all factors relating toweapon pointing. The aim processing means may also convert these factorsto input control signals. The aim processing means preferably includes acomputer or digital processor or a partitioned part thereof. The aimprocessing means may have knowledge of the position, motion limitsand/or characteristics of the weapon mounting system for scaling theinput control signals to optimise the weapon mounting system response.Preferably, the input control signals are scaled so that the correctpointing of the weapon is obtained in the shortest possible time.

For simple applications or missions, the processing requirements of theAWS are preferably consolidated into one or more processors. Forexample, the image processing means, the track processing means, thecorrection processing means, the aim processing means, and/or the firingcontrol means may not have dedicated processor(s) for each function.

The weapons mounting system preferably includes a two axis motor drivengimbal that supports a weapons cradle. Servo electronics are preferablyprovided to amplify the input control signals with sufficient gain andband width to maintain stable control of the two axis gimbals under thedynamic force loading of typical engagement scenarios.

The weapon mounting system is preferably configured to interchangeablyaccept a number of weapons such as the M2, MK19 and M60 machine guns.

The AWS can include a laser range finder which provides an input to thetargeting means to more accurately determine the appropriate pointing ofweapons, including ballistic weapons. This rangefinder preferably hasthe capability to measure the range to a specific projectile fired bythe weapon as that projectile moves away from the weapon for determiningthe actual muzzle velocity under the specific circumstances ofengagement. This data is important for accurate engagement at longerranges, and can only be estimated prior to the firing of the weapon. Therangefinder preferably has a receiver which is sensitive to the spatialfrequency of the energy reflected by the projectile for determining thedirection of the projectile. This information may be required forestimating down-range perturbation forces such as wind.

In one form of the invention th imaging system captures radiationemitted by or reflected from the target. In other forms of the inventionth targ t may be irradiated for example with laser light from a sourcemounted with the weapon, and either the spatial intensity modulation ofthe reflections, or the reflection spectrum itself, can be used todetect or classify targets.

The threat profile, external cueing, and other target identificationcriteria may be used to significantly reduce the amount of processingrequired by the image processing means. For example, the criteria may beselected according to the environment in which the weapon is operated sothat it seeks only targets that will be found in that type ofenvironment. Thus in a marine environment the weapon might not considervehicles or personnel as possible targets but may for example givepriority to seeking missiles, aircraft or vessels. Aircraft might besought only above the horizon, and vessels only below, with missilessought throughout each sensor field of view.

The invention overcomes deficiencies of prior art by removing the humanoperator from the closed loop control system that aims and fires theweapon. However, this step is not possible without simultaneouslyintegrating a fail-safe capability to interpret and implement rules ofengagement for the weapon.

The AWS provides the following performance features, overcomingdifficulties or deficiencies in prior art and implementing additionaladvantages not accessible by prior art:

Accuracy. The weapon firing is controlled by electronic impulsesobtained by processing data from sensors that can accurately determinethe position of the weapon aimpoint (e.g. where the barrel of the weaponis aimed) relative to the selected target at any time, and specificallyprior to weapon firing. The result is unprecedented accuracy in bothsingle shot and burst modes of firing.

Ergonomics. Since the weapon firing is independent of humanintervention, system ergonomics are excellent. The human operator of theweapon acts as a supervisor of the weapon systems, providing high levelinput such as cueing commands, target prioritising, and s tting rules ofengagement. Thes activities are not required to be performed inreal-time, so both the gunnery and other operator tasks are enhanced.

Stabilization. The AWS incorporates sensors that can determine theposition of the weapon aimpoint relative to the selected target at anytime, and with a high frequency of update. Any relative motion, whetherdue to motion of the target or the weapon, is measured and aimpointcorrects are applied automatically through the weapon drive motors.These corrections can incorporate a full or partial fire controlsolution, depending on the availability of sensor data.

Surveillance. The enhanced mobility and lethality of the autonomousweapon systems brings about a convergence between surveillance andengagement assets. The traditional separation of these roles is notrequired, because the sensor array of the AWS can be utilized fortraditional surveillance applications, with significant costs savings.

Recording. The weapon system can record the target image at any time,including for each engagement. This has advantages in battle damageassessment as well as providing an audit trail for compliance with rulesof engagement. Developments in international law as applied to the useof military force can place the onus of proof of compliance on thegunner. This system clinically implements pre-programmed rules ofengagement, and includes strong firing veto powers to the off-lineoperator as well as an audit trail.

Sensor integration. Because the system operates without humaninvolvement in the closed loop control system, integration of additionalsensors, co-located with the weapon or remote from it, is possible. Byway of example, acoustic direction-finding sensors do not interfacereadily with human gunners, but integrate seamlessly with the AWS toprovide cueing data for internal sensors.

Peripheral vision. One of the most problematic areas in the developmentof remote weapon systems has been the difficulty associated withproviding the gunner with situation awaren ss comparable to thatavailable to traditional gunners, through the panoramic vision availablein the exposed firing position. Multiple wide-field camera systems cancapture the required data, but no satisfactory means of presenting thisdata to a remote gunner has been developed. Multiple screen displayshave been unsuccessful, even when integrated into a heads-up display.The AWS according to the invention is intrinsically suited to parallelimage processing of multiple frames that cover up to 360 degrees ofvision. The image processing and analysis are substantially the same asapplied to the frontal field of the weapon system, allowing the systemto retain an enhanced level of situation awareness. The system caninclude sufficient processing power to implement peripheral vision withdata provided to both the main sensors and the operator (if present).

Delayed fire mode. The AWS may include a synchronous firing mode thatallows for induced oscillations of Fe weapon aiming position to becompensated by delaying the firing of individual shots from the weaponto the exact point of optimum alignment of the aimpoint, allowing forsystem firing delays.

Expert system. The AWS may include sufficient processing power toimplement a learning program that allows the system to progressivelyimprove the interpretations it applies to its operator inputs, as wellas engage targets with enhanced effectiveness. The AWS may include atarget database that is retained and used by the image processing meansto classify targets as well as to select specific soft points on eachtarget to engage if cleared to fire. For example, the sensors on a mainbattle tank are specifically initially targeted by this system, ratherthan the tank itself, and the system can learn new sensor configurationsand placement for each type of tank.

IFF compatibility. Casualties from friendly fire are a major problem formodem combatants, largely due to the pace of modem combat and reducedreaction times. Autonomous weapon systems potentially exacerbate thisproblem, if deployed with aggressive rules of engagement. However, theinvention includes electronic support for an external IFF (identifyfriend or foe) firing veto, with virtually instantaneous response. Thismeans that in addition to the applicable rules of engagement and theremote operator firing veto, the weapon can accept a real-time firingveto based on any IFF protocol in use at the time of deployment.

User identification. The AWS may include within its processors thememory capability to store identification data for as many users ass areever likely to be authorized to use the system. The identification datamay include retinal scan, voiceprint, fingerprint, or other biometricdata for each authorized modification.

Low power. The AWS may include power-saving features to allow it to bedeployed unattended for extended periods using battery power.Lightweight, battery-operated systems can be deployed with specificrules of engagement to deny mobility or terrain access to an enemywithout the disadvantages of deploying mines. A wireless link to theweapon operator can be maintained to allow arbitration of weapon firing.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, referred to herein and constituting a parthereof, illustrate preferred embodiments of the invention and, togetherwith the description, serve to explain the principles of the invention,wherein:

FIG. 1 shows the principal components of the AWS according to theinvention, in functional schematic form;

FIG. 2 shows another implementation of the invention, with additionalsensors according to the invention, in functional schematic form.

FIG. 3 shows a physical representation of the AWS in a basicimplementation for a ballistic weapon system.

FIG. 4 shows the sensor systems, image processing, tracking computer,ballistic computer, and ancillary electronics packaged as an integratedunit (“Sensor Unit”), and with the case removed to expose keycomponents;

EMBODIMENTS OF THE INVENTION

(a) System Overview: AWS

Electro-magnetic energy reflected or radiated by the target [1] isdetected by the imaging sensors [2]. Typical imaging sensors include CCDor CMOS cameras, intensified CCD or CMOS cameras, high quantumefficiency CCD or CMOS cameras operating at very low light levels,thermal imaging cameras, and bolometric thermal sensors.

A single imaging sensor is sufficient to provide an image that meets thebasic requirements for the AWS to operate. However multiple sensorsoperating in both visible and infrared spectrums, and with theircombined data used to make decisions in respect of target detection,provide improved performance.

The image(s) from the sensor(s) are passed to the image processor [3]where they are digitally enhanced and processed to detect and classifyobjects of interest.

Once the image processor [3] has detected and classified a target, itsposition and motion relative to the boresight of the sensor system isdetermined on the basis of information contained within successive imageframes by the tracking computer [4]. If the target is in motion relativeto the weapon (ie. if either the target or the weapon is in motion) morethan one image frame is required to obtain useful results from thetracking computer.

The tracking computer determines the pointing angle corrections tocompensate for present pointing errors, platform motion, and expectedtarget motion.

At the sam tim a target rang estimation is made by the imag processor[3], based on visual clu s within th images, or by means of a laserrangefind r [12]. This rang is provided to the ballistic computer [5] toallow range-dependent weapon lead angle and elevation to be included inthe pointing commands provided to the weapon servo system [7].

Additional platform sensors [11] mounted on the weapon platform providephysical and environmental data for higher precision aimpointdetermination for ballistic weapons.

The tracking computer combines all pointing angle corrections to obtaina single command (per axis of the weapon gimbal) that is passed to theservo system. The servos [7] amplify the angle commands to provide drivecommands for the gimbal drive motors, located on the gimbal [8].

The weapon [9] is fired under the direct control of the ballisticcomputer [5] which strictly adheres to pre-set rules of engagement, andis subject to a firing veto from the operator via the communicationslink.

A communications [6] interface allows an operator [10] to providecommands and support for the system. The communications interface mayconsist of a cable or wireless link.

The AWS provides a closed-loop system commencing with the targetradiating or reflecting energy, and ending with the accurate delivery ofmunitions to the target position. There is no human operator or gunnerin the closed-loop process. The operator does have a role innon-real-time processes that enhance the closed-loop response.

(b) Sensor [2]

The sensors include at least one imaging system to allow the weapon tobe aimed at the target, or at the correct aimpoint to engage the targethaving consideration of the munitions, target range, and other aimingfactors.

(c) Image Processor [3]

The image processor [3] consists of:

-   an input buffer memory, made up of multi-port or shared memory,    where the output of various sensors is temporarily stored, and where    it can be read by the image processor as well as written by the    sensors;-   a digital signal processor (“DSP”) typically operating with a clock    speed of 500 MHz, but which can be slowed under program control to    conserve power and reduce electromagnetic emissions; and-   an output buffer memory, where the output image frames are stored in    various formats, including summary formats containing only target    identification and its position, prior to display or communication    or re-entry into the image processor for additional processing.

The digital data from the sensors is normally transferred to the DSP inblocks, representing an image frame for the sensor. Multiple sensors canbe synchronized by the image processor such that they operate at thesame frame rate, or such that every sensor operates at a frame rate thatis a multiple of the slowest frame rate used. This expedites frameintegration and data fusion from multiple sensors, because common timeboundaries can be used to merge sensor data.

The DSP operates in a processing loop based on the fastest frame rate,and in a sequence that typically uses the following steps:

-   The data from individual sensors is optimised. Sensor data for each    sensor is corrected by the DSP for image distortion, damaged pixel    infill, pixel responsiveness variations, and other sensor defects    that can be mapped, calibrated or corrected.-   Sensor data is enhanced. Typically, contrast enhancement is sought    by applying a variety of digital filters to the sensor data. The    filters include contrast stretch, chromatic stretch, temporal    filtering, spatial filtering, and combinations of these. The filter    mix is tuned until an objective imag criteria set indicat th frame    has been optimised. In practice, the DSP us s a fixed number of    filter combinations, pre-tested for their effectiveness, and    filtering can also be applied according to pre-determined filter    sets, rather than by inter-active tuning of the filter sets.-   The DSP determines whether there is any useful information in the    sensor data after enhancement. In many instances the data comprises    only noise, and the DSP can conserve power by avoiding further    operations.-   Image features are tested for similarity with possible targets,    which have been ranked according to probability and risk by operator    commands. This ranking is referred to as the threat profile, and the    DSP has access to a catalogue of standard profiles that can be    invoked by the user by reference.-   Possible fits of image features with a threat result in user alert,    and closer scrutiny of the image features, possibly by means of    additional sensors of by zooming a sensor for more detailed    examination. Threat classification requires significant system    resources, and this step benefits greatly from user intervention,    based on image fragments being relayed to the user for comment.    Multiple potential targets can be detected and classified in this    way-   An image provided to the tracking computer and the user, if    connected. This image may be an enhanced frame from a single sensor,    a compound frame arising from fusion of data from more than one    sensor, or a numeric sequence that provides the system status,    including the target description and its location in the field of    view of the sensor.

The effectiveness of the signal processing algorithms employed issubstantially enhanced by narrowing the scope of the search algorithms.This is done by one or more of the following:

-   seeding of the target classification process with a priori knowledge    of the scene; or-   reducing the region within the sensor frame that is processed to    some subset of the frame as indicated by a separate cueing system;    or-   restricting the scope of the processing algorithms to a specific    class or classes of target such as watercraft, armoured vehicles,    personnel, or aircraft; or-   structuring the search process to use specific spectral imaging    bands corresponding to the emission or reflection spectra of typical    or expected targets; or-   restricting the algorithm to operate only on image movement in one    or more spectral bands; or-   any combination of these factors.

The factors used by the image processor are installed by the operator atany time prior to, or even during, an engagement. The image processorframe throughput improves from 0.2 frames per second to over 30 framesper second if sensible use is made of these factors to reduce the scopeof the threat detection and classification algorithms.

(d) Tracking Computer [4]

The tracking computer [4] operates on data provided by the imageprocessor [3]. Its function is to:

-   examine successive frames to determine the current pointing error of    the weapon and the likely error over the next short interval    (typically 200 milliseconds);-   add the ballistic correction angles provided by the ballistic    computer; and-   output the net pointing correction to the servo system.

The tracking computer checks for motion by detecting pattern movement,based on potential targets or features identified by the image processor[3]. A motion algorithm separates whole-frame motion from partial-framemotion. Partial-frame motion is likely to b subsequently classified astarget motion, and whole-frame motion is likely to be subsequ ntlyclassified as weapon motion.

(e) Ballistic Computer [5]

The ballistic computer is also the firing control computer.

The ballistic computer determines a “fire control solution”(conventional terminology) for ballistic weapons to the extent thatsensor and other input data is available. The ballistic computerprovides this information to the tracking computer [4] in the form of anincomplete solution that is ultimately solved by the tracking computer[4], which provides the last required variables from its real-timeanalysis of sensor images.

The real-time task of the ballistic computer [5] is to control thefiring of the weapon, including ensuring full compliance with the rulesof engagement. This function is fail-safe so that the weapon will disarmitself on failure.

The ballistic computer [5] contains a catalogue of rules of engagement,with several scenarios for each mission profile. Typical missionprofiles include reconnaissance patrol, infantry support, stationaryfiring zone, asset protection, sniper suppression, defensive withdrawal,peacekeeping patrol, firing suppression with area fire, interdiction andnon-lethal intervention. For each mission there are specific rules ofengagement and within each set of rules there are escalating levels ofresponse leading to lethal firing of the weapon.

Every set of engagement rules supports user veto if required by theuser. The veto or over-ride can be exercised prior to the engagement bythe user selecting levels of response for individual targets before anengagement commences.

The choice of targets and their engagement sequence is made by theballistic computer, based on the threat level presented by each target,and the rules of engagement.

(f) Communications [6]

The communications [6] between the operator and the weapon system allowsthe operator to provide commands and support for the system. Theoperator may, either by reference to standard internally-storedscenarios or directly:

-   update or alter the operating software for the system;-   provide the system with new or amended rules of engagement, or    command that a new set of rules from within the weapon system memory    be applied;-   provide the system with risk profiles or command that a new profile    from within the weapon system memory be used to allow processor    effort to be allocated and expended in proportion to the risk posed;    or-   provide manual or external cues or sensor readings to improve the    effectiveness of the system;-   provide target priorities, and/or updates on optimum attack points    for specific targets;-   request transmission of image, status, or sensor data; or-   require case-by-case veto over the firing of the weapon.

The communications between operator and AWS can function over verylimited bandwidths, but can also make use of video bandwidths, ifavailable, to allow the operator to observe various sensor outputs. TheAWS will optimise its communications to suit the available bandwidth tothe operator.

Video bandwidths (MHz bandwidth) are available if the operator islocated close to the weapon, where cable, optical fibre, or widebandwireless links may be used. In this case, the operator can effectively'see all that the AWS sensors can “see”.

If the communications link has kHz bandwidth, then the system willtransmit simple status information, including summary target and statusin numeric form, referencing known target types. An image fragment, asrequired for the operator to xercis a firing veto, requires around 3seconds of transmission tim on a 8 kbaud communications link. This isoperationally viable.

(g) Servos [7]

The servos must provide sufficient power gain, and with sufficientbandwidth, to allow the weapon gimbal to point as commanded despite awide range of perturbing forces that include weapon shock and recoil,platform vibration (eg. from a vehicle), and wind buffet.

The servos are designed such that the natural frequencies of the weapongimbal and servo (combined) do not correspond with any predictedexcitation of the weapon system, including but not limited to itspreferred firing rates.

(h) Gimbal and Cradle [8]

The weapon cradle supports the weapon so that boresight between theweapon and its sensors is retained, to the precision of the weapon anddespite the firing shock of typically deployed ballistic weapons, whichcan exceed 50 g (ie. 50 times the force of gravity).

Depending on the weight limits imposed on the system, and its dynamicperformance requirements, the gimbal and cradle can be fabricated fromor include metallic or ceramic armour to provide protection to thesensors and electronics of the AWS.

(i) Weapon [9]

The AWS is suitable for deploying all direct fire weapons. The weaponsrequiring the most complexity in the AWS are ballistic weapons, becausethey have “dumb” munitions (ie. the aiming of the munition cannot beimproved after it has been fired) and they are susceptible to the widestrange of environmental parameters. These parameters include weaponcharacteristics (eg. barrel wear, barrel droop with temperature),ammunition characteristics, atmospheric variables, range target motion,weapon motion, and distance to the target.

Ballistic weapons firing ammunition that requires in-breach fusing arealso suitable for deployment on the AWS because the setting of fuses issimplified by the integrated range determination systems.

Close range missiles (eg. TOW, STINGER) have smart munitions withsensors that are effective over a narrow field of view. These weaponsachieve optimum efficiency when deployed on AWS, because the weaponarming, uncaging, and firing are supported by electro-optic and othersensors that are more effective in terms of target discrimination andselection than the simplified sensors deployed in the missilesthemselves.

Directed energy weapons are simply adapted to the AWS. These weaponsrequire extremely small lead angles, and are independent of gravity andenvironmental factors, in terms of aimpoint. The AWS automaticallydiscards all ballistic algorithms if deployed with directed energyweapons, at the same time introducing corrections for atmosphericrefraction and firing delay (typically 1–2 milliseconds). Theatmospheric refraction corrections are required if the weapon wavelengthand the sensor wavelength are not similar, and are particularlyimportant for applications where the weapon and the target may be atdifferent atmospheric densities.

(j) Platform Sensors [11]

The AWS uses data if available, from sensors mounted on the weaponplatform to determine parameters that influence the aiming of theweapon. These parameters include:

-   -   Temperature, which impacts the droop angle of the barrel and the        combustion rate of ballistic propellant;    -   Atmospheric pressure, which impacts propellant burn rate (muzzle        velocity);    -   Weapon cant angle, which rotates the axes of the sensors        boresight d to the weapon and must th refore be measured if        accurate aimpoint calculations are to be obtained (included in        “Inertial reference coordinates”, below);    -   Target elevation, which requires additional aimpoint adjustment        due to the potential (gravitational) energy difference between        weapon and target weapon and must therefore be measured if        accurate aimpoint calculations are to be obtained (included in        “Inertial reference co-ordinates”, below);    -   Weapon rotation rate (on each axis of potential rotation); which        can be otherwise confused with target motion;    -   Position (both absolute and relative) as measured by (eg.) GPS,        which can be used to enhance AWS sensor cueing by external        sensors such as acoustic sensors deployed on known map grid        positions; and    -   Inertial reference co-ordinates, that may be used to resolve the        direction of gravity under all conditions, allowing accurate        calculation in real time of the forces applying to ballistic        munitions.

In practice, an inertial reference system is highly desirable if theweapon platform is mobile or maneuverable, whereas the measurement ofcant and target elevation may be sufficient for slowly moving orstationary weapon platforms.

(k) Rangefinder

The formulation of an adequate ballistic solution for any target beyondabout 500 m in range depends on the accurate determination of the rangeto the target.

Although the AWS can determine the target range approximately by usingthe pixel scale of the image, this may not be adequate for allapplications.

A laser rangefinder is commonly included in the AWS configuration toprovide an accurate determination of the range to the target.

The AWS uses weapon type, ammunition type, and meteorological parametersto predict the muzzle velocity for ballistic weapons. The weaponaimpoint is very strongly dependent on munition muzzle velocity, and itis advantageous if this is obtained by measurement rather than inferredindirectly. For most ballistic munitions, two laser range measurementsmade approximately one half-second apart and after the munition has leftthe weapon barrel will allow a very accurate estimation of muzzlevelocity. The AWS laser rangefinder can measure range in 2 Hz bursts toprovide accurate muzzle velocity measurements.

The fall of ballistic munitions can be determined with high accuracy ifall significant environmental parameters are known. In practice the mostdifficult parameters to estimate are the transverse and longitudinalforces (eg. wind) along the munition flight path to the target. The AWSlaser rangefinder includes a gated imaging system that is sensitive atone of the emission lines of the AWS laser.

Using the firing epoch of the munition and its known muzzle velocity,the munition is illuminated by the AWS laser before it reaches thetarget range. An imaging system that is sensitive to the laserwavelength is gated in time to show an image that includes laser lightreflected by the munition. The transverse location of the munition imageallows the integrated transverse forces applying to the munition alongthe flight path to be determined.

By this means, the aiming point of the weapon can be corrected evenbefore the first round has approached the target.

(l) Operator [10]

The operator [10] is the AWS supervisor and mentor. As described above,the communications link between the system and the operator may vary inbandwidth from zero to several MHz. The type of communication betweenoperator and system will depend on the nature of the communication link,and the tactical situation.

Typical scenarios are:

-   -   The AWS is deployed on a vehicle with the operator conveyed in        the vehicle. In this case the data link is a simple RF cable        connected to the operator's visor display, or an equivalent        intra-vehicle wireless link. Operator input is by voice, motion        (including eye motion), or manual entry. To the extent that he        is able, the operator provides cues to the image processor and        the tracking processor to expedite threat classification,        prioritising and tracking. The operator also can control the        target engagement sequence and rules of engagement for each        target. Rules of engagement can be suspended for small angular        sectors for short intervals, in target-rich environments.    -   AWS deployed unattended. The unattended AWS will normally        default to low-power surveillance mode, where it continually        monitors the zone of terrain allocated to it. This may be done        using a single cueing sensor such as a thermal imager or        acoustic sensor. Detection of a target progressively brings        weapon system sensors on line, until the target is classified        into an appropriate category. At this stage the operator may be        alerted, with data that may comprise a full or partial image        frame, or simply a numeric identification of the status of the        system and the number and type of targets. The target(s) will be        engaged according to the rules of engagement applying.

The field of view of the sensors must be sufficient to allow the targetto be viewed at the same time as the aimpoint is set to the correctposition to engage the target. In practice this stipulates that theweapon elevation angle required for the munition to reach the targetmust be less than the vertical field of view of the sensor used forengagement. Similarly, it stipulates that the lead angle required by thetransverse motion of the target is less than the horizontal field ofview of the sensor used for engagement.

The reference to any prior art in this specification is not, and shouldnot be taken as, an acknowledgement or any form or suggestion that thatprior art forms part of the common general knowledge in Australia.

It is understood that various modifications, alterations, variations andadditions to the constructions and arrangements of the embodimentsdescribed in the specification are considered as falling within theambit and scope of the present invention.

1. An autonomous weapon system that can engage targets without humanintervention at a time of engagement, said system comprising: a weaponto be fired at a target; a weapon mounting system operable to point theweapon in accordance with input control signals; a sensor system toacquire image data from a target zone; image processing means to processsaid acquired image data and identify potential targets according topredetermined target identification criteria; targeting means to providesaid input control signals to said weapon mounting system to point theweapon for firing at a selected one or more of said potential targets;and autonomous firing control means to operate said targeting means andfire the weapon at said selected potential targets, or to preclude orlimit such firing, according to a predetermined set of rules ofengagement stored in said system.
 2. An autonomous weapon system asclaimed in claim 1 further including communication means to provide fortransmission of data between the weapon system and a remote controllocation.
 3. An autonomous weapon system as claimed in claim 2 whereinsaid communication means provide for the overriding of the firingcontrol means from said remote control location to prevent firing of theweapon.
 4. An autonomous weapon system as claimed in claim 2, whereinsaid communication means provide for amendment of the rules ofengagement from said remote control location.
 5. An autonomous weaponsystem as claimed in claim 1, wherein said firing control meansautonomously interprets said rules of engagement according to a threatprofile of target identifying criteria.
 6. An autonomous weapon systemas claimed in claim 1, wherein said sensor system includes one or morecameras operating at the visible, intensified visible or infraredwavelengths producing images compatible with digital processing.
 7. Anautonomous weapon system as claimed in claim 1, wherein said imageprocessing means includes pre-configured threat profiles to seek targetsaccording to the level of threat posed by specific targets, or theprobability of encountering a specific target, or both.
 8. An autonomousweapon system as claimed in claim 1, wherein said targeting meansprovides the input control signals based on pointing correctionsrequired for the weapon to hit the target.
 9. An autonomous weaponsystem as claimed in claim 1, wherein said firing control means includesa fail-safe autonomous control of the firing of the weapon by referenceto specific rules of engagement stored within the system.
 10. Anautonomous weapon system as claimed in claim 1, wherein said rules ofengagement include at least one of combat, peacekeeping, or policingscenarios.
 11. An autonomous weapon system as claimed in claim 10wherein said rules of engagement include provision for an enduring vetoon selected modes of operation of the weapon.
 12. An autonomous weaponsystem as claimed in claim 1, further comprising track processing meansto process said acquired images or data to determine the correctpointing angles for the weapon to compensate for platform or targetmotion.
 13. An autonomous weapon system as claimed in claim 12 whereinthe track processing means resolves all motion to a local quasi-inertialreference frame so that the track processing means has access to datafrom such a frame.
 14. An autonomous weapon system as claimed in claim1, further comprising a laser range finder which provides an input tothe targeting means to determine the appropriate pointing of weapons.15. An autonomous weapon system as claimed in claim 14 wherein therangefinder measures the range to a specific projectile fired by theweapon as that projectile moves away from the weapon for determining theactual muzzle velocity under the specific circumstances of engagement.16. An autonomous weapon system as claimed in claim 14, wherein therangefinder has a receiver which is sensitive to the spatial frequencyof the energy reflected by the projectile for determining the directionof the projectile.
 17. An autonomous weapon control system forcontrolling a weapon to be fired at a target using a weapon mountingsystem operable to point the weapon in accordance with input controlsignals, said weapon control system comprising: a sensor system whichacquires image data from a target zone; image processing means forprocessing said acquired image data and identifying potential targetsaccording to predetermined target identification criteria; targetingmeans for providing said input control signals to said weapon mountingsystem to point the weapon for firing at a selected one or more of saidpotential targets; and autonomous firing control means for automaticallyselecting targets from among said potential targets, and for causingsaid weapon to fire, or not to fire, at said selected targets, or forlimiting such firing, according to a predetermined set of rules ofengagement stored in said system.
 18. An autonomous weapon controlsystem, comprising: a weapon to be fired at a target; a weapon mountingsystem operable to point the weapon in accordance with input controlsignals; a sensor system which acquires image data from a target zone;image processing means for processing said acquired image data andidentifying potential targets according to predetermined targetidentification criteria; targeting means for providing said inputcontrol signals to said weapon mounting system to point the weapon forfiring at a selected one or more of said potential targets; andautonomous firing control means for automatically selecting targets fromamong said potential targets, and for causing said weapon to fire, ornot to fire, at said selected targets, or for limiting such firing,according to a predetermined set of rules of engagement stored in saidsystem.